A census of the population of the United Kingdom is taken every ten years. The 2011 census was held in all countries of the UK on 27 March 2011. It was the first UK census which could be completed online via the Internet. The Office for National Statistics (ONS) is responsible for the census in England and Wales, the General Register Office for Scotland (GROS) is responsible for the census in Scotland, and the Northern Ireland Statistics and Research Agency (NISRA) is responsible for the census in Northern Ireland.
The Office for National Statistics is the executive office of the UK Statistics Authority, a non-ministerial department formed in 2008 and which reports directly to Parliament. ONS is the UK Government's single largest statistical producer of independent statistics on the UK's economy and society, used to assist the planning and allocation of resources, policy-making and decision-making. ONS designs, manages and runs the census in England and Wales. In its capacity as the national statistics office for the United Kingdom, ONS also compiles and releases census tables for the United Kingdom when the data from England and Wales, Scotland and Northern Ireland are complete.